The present invention concerns a pneumatically and/or electromotively actuable disc brake.
Disc brakes are known, e.g. as sliding caliper disc brakes, swivel caliper disc brakes, or fixed caliper disc brakes.
Sliding caliper disc brakes require a fixed-axis component or carriers, which carries the brake linings effective at one side of the disc brake, and which absorbs its peripheral force when the disc brake is activated, and also holds the caliper displaceably lodged in parallel to the axis of the vehicle. The relative movement, which the caliper performs against the fixed-axis component, can be divided into a power stroke and wear stroke.
To balance the wear of the brake lining and/or disc brake, at least one adjustment device is arranged in the caliper, which acts upon the brake lining by means of one or two pressure pieces that are displaceable essentially axially to the disc brake, in order to adjust the distance between the brake lining and the brake disc.
If separate adjustment devices are arranged on both sides of the brake disc, it is merely necessary to align the displacement path of the brake disc in such a way that the release clearance can be overcome and the elastic deformation of the brake lining and the caliper, in other words the power stroke, can be balanced out (see e.g. PCT/EP01/09366).
The adjustment devices provided on both sides of the disc brake consist e.g. of adjustment sleeves, which, as adjustment elements of an electric motor or another mechanical device, are pivotable via a gear. These adjustment sleeves consist of an inside thread, into which a bolt-like spindle of the respectively thereto arranged pressure piece is screwed, so that with appropriate rotation, a relative axial movement is provided between the adjustment sleeves and the pressure pieces. Also known is a reverse arrangement, in which the pressure pieces have a sleeve-like spindle, which is pivotable on a bolt that forms the adjustment element.
The brake lining material is directly connected to the lining support, which in turn is either connected with the pressure piece, or rests against the pressure piece “loosely” without connection.
From German Patent document DE 42 30 005 A1, a disc brake with a sliding caliper is known, in which on each side of the disc brake, two pressure pieces arranged next to one another each act on a lining support of a brake lining, which is equipped with a lining support material.
A disadvantage of these known constructions lies in the fact that the frictional heat that is generated during a braking action is conducted through all components of the adjustment device without any blockage, whereby the downstream functional elements are exposed to a special stress, which reduces the service life. This is especially of concern when electric motors are employed as drive units for the adjustment devices.
Since disc brakes, which are utilized in utility or commercial vehicles, are subjected to the highest stresses, this issue is of particular significance, especially in terms of economy, since a shortened service life, and consequently the replacement of the corresponding functional elements, entails not only repair costs, but also costs that arise from the necessary out of service time of the utility vehicle.
From German Patent document DE 39 19 179, a disc brake is known, in which, at the side of the brake lining that faces the pressure piece, an insulating board is mounted at the lining support, which reduces the flow of heat between the brake lining and the pressure piece. Since a high generation of heat at the brake disc and the brake linings is obtained with braking, the insulating board protects the inside of the caliper—that is the brake application unit and the adjustment device—against overheating. The problem can be minimized by means of this solution.
It is also necessary to keep the pressure pieces and the adjustment elements torsion-resistant, in order to achieve, in conjunction with stationary, yet pivotable corresponding elements, such as adjustment sleeves with an inside thread, in which the adjustment elements are provided as a thread spindle, an axial movement of the thrust pieces.
The present invention is, therefore, based on the objective of further developing a disc brake of the above-mentioned type such that, with constructively minor measures, on the one hand during braking actions a reduced heat conduction into the inside of the caliper, and/or a constructively simple method for securing torsion-resistance of the adjustment elements and their corresponding elements, is achieved.
This objective is attained with a pneumatically and/or electromotively actuable disc brake for a utility vehicle, having a caliper that straddles a disc brake, at least one brake application unit arranged in the caliper for clamping the disc brake, and at least one adjustment device arranged in the caliper to offset brake lining wear, and/or brake disc wear by adjusting a distance between at least one brake lining, and the brake disc, which consists of two axially displaceable adjustment elements, each with a pressure piece, wherein the two adjustment elements of the at least one adjustment device are fixed torsion-resistantly in their areas that face the respective brake lining at a common connection plate, and/or at the connection plate, and/or at the pressure piece on the side facing the respective brake lining, a single- or multi-part heat-insulting layer is attached at least section-wise.
Accordingly, the two adjustment elements of the at least one single adjustment device, are attached torsion-resistantly in their area facing their respective brake lining, on a common connection plate; and/or at the connection plate, and/or at the pressure piece on the side facing the respective brake lining a one-part or multi-part heat-insulating layer(s) is/are attached at least in sections.
As compared with the state of the art, this connection plate in its function as securing torsion-resistance offers not only substantial advantages as far as production and assembly are concerned, due to its simple construction, but also functional advantages, since the connection plate always remains at the same position on the pressure pieces, i.e. the connection plate moves according to the axial displacement of the pressure pieces along with them.
Thereby, in addition to the constructively uncomplicated securing of torsion-resistance of the pressure pieces, a protection of the downstream functional components from the effects of heat is also effectively enabled via simple means; this is achieved on the one hand by the connection plate itself, and on the other hand by the layer on this plate, or at the pressure piece.
Thereby, strain caused by the excessive heating of the parts arranged in the inside of the caliper, or an impairment of their ability to function during continuous or frequent heating with the resulting issues described in the state of the art, are prevented.
Preferably, the connection plate is realized as a thermal shield, which is dimensioned in such a way that it covers the opening of an installation space in the caliper, in which the adjustment device is placed, covered to a large extent. In addition, the opening may be closed by a further cover plate, which is screwed in at the opening of the caliper, and therefore is not axially displaceable, and has breakthroughs for the thrust elements.
It is extremely advantageous if the heat-insulating layer is realized in one part or several parts, and is directly mounted onto the connection plate. The layer may consist of one or two ceramic plates, which protrude over the pressure piece beyond its largest diameter dimension, wherein this ceramic plate is mounted on the connection plate, which is connected form flush and/or force flush with the pressure pieces, and which functions as heat protection, and as a device for securing torsion-resistance for the two pressure pieces of an adjustment device.
According to a further preferred modification, a pressure piece that forms the thrust piece plate is positioned upon the connection plate, and supports the heat-insulating layer. It is also contemplated, however, to place a ceramic layer on the pressure piece plate. In this manner, the connection plate is clamped by the pressure piece plate.
Preferably, the pressure piece plate is held at the connection plate form flush in an axial direction and torsion-resistant.
Especially preferably, the pressure piece plate has recesses that face the connection plate, which are contact-free in the material.
According to a further advantageous modification, the connector plate, in turn, has protuberances in the connection area with the adjustment elements facing the brake lining, in which protuberances the adjustment elements are appointed in a simple manner axially, and torsion-resistantly.
It is thus a further advantage for the cylinder-shaped protuberance to have stop notches formed in its surface area, which are realized in the interior of the protuberance in the form of catch grooves, and which on the outside correspond to catch grooves on the pressure piece plate, and on the inside correspond to noses of the adjustment element, and thus especially allow for a simple assembly of these constructional elements.
According to a further modification, the area embedded in the protuberance of the adjustment element has on its surface side slots that break through the material. In order to achieve optimized heat insulation, the pressure piece plate may also be provided with breakthroughs, which are, for example, arranged next to one another in a radial direction, and which effect heat insulation in this area. In each of these cases, the pressure piece plate and the pressure piece are connected torsion-resistantly to the connector plate.
In addition, expansion bellows may be connected at the connector plate, covering the respective adjustment elements as protection.
According to a further—also to be considered separately—modification of the invention, the pressure pieces and the lining support are each connected to one another in such a way that—continuously and in a simple way—a retraction of the brake lining is guaranteed, when the adjustment elements are turned back and when the brake is released.
With respect to the construction, it is a special advantage if, at the pressure piece, or at a component of the adjustment element connected with this, one or several plate springs are arranged, which undercut a rod in a recess of the lining support. As an alternative, one or more plate springs may be arranged at the lining support, which undercut the pressure piece or a component of the adjustment element connected to it.
Further advantageous embodiments of the invention are described and claimed herein.
Exemplary embodiments of the invention are described in the following by way of the enclosed drawings.